1. Field of the Invention
The invention relates to a cooler, and particularly, to a cooler that ejects coolant from nozzles to heat radiating fins.
2. Description of Related Art
In a hybrid automobile or the like, a power module is used, which includes a semiconductor device such as an inverter circuit that performs power conversion. In recent years, as such a power module has been downsized and an output thereof has been increased, generation of heat in the power module has become a large problem. Accordingly, a compact and high-performance cooler is desired, which effectively cools the heat generated in the power module or the like.
As a related art of such a cooler, for example, an impinging jet cooler described in Japanese Patent Application Publication No. 2011-166113 (JP 2011-166113 A) is known. The impinging jet cooler jets coolant from nozzles, and flows the coolant into fins, thereby cooling a heating element brought into contact with the fins.
FIG. 9 is a perspective view showing an internal configuration of the cooler according to the related art, which is described in Japanese Patent Application Publication No. 2011-166113 (JP 2011-166113 A). As shown in FIG. 9, the cooler 900 according to the related art includes: a base plate 903; a plurality of fins 902 arrayed on the base plate 903; and nozzles 901 which eject coolant to the plurality of fins 902. The nozzles 901 are composed of a nozzle member 911 formed into a wave shape, and coolant supply holes 912 are formed on fin 902-side apexes of the nozzle member 911. The coolant flows through inflow passages 913 formed of the nozzle member 911, and the coolant in the inflow passages 913 is ejected from the coolant supply holes 912 to regions between the fins 902, whereby a cooling target attached onto the base plate 903 is cooled.
FIGS. 10A and 10B are cross-sectional schematic views of the cooler of FIG. 9, which is according to the related art and is taken along a line A5-A6: FIG. 10A shows a state before the coolant is flown; and FIG. 10B shows a state at a time when the coolant is flown.
As shown in FIG. 10A, onto the base plate 903, a semiconductor device 922 is attached through an insulating layer 921, and the fins 902 are arrayed on a case body 904 that uses the base plate 903 as a bottom portion thereof. A case cover 905 is adhered onto an end portion of a base side wall 904a of the case body 904 through end portions of the nozzle member 911, and an inside of the cooler is hermetically sealed.
Here, in an actual cooler, dimensional tolerances are present in the respective components, which are the nozzle member 911, the fins 902 and the case body 904. If the inside of the cooler is attempted to be hermetically sealed as shown in FIG. 10A, for example, in a case where a height of the nozzles 901 is higher than a standard thereof owing to the tolerance, then a gap could occur between the end portion of the nozzle member 911 and an end portion of the case body 904.
However, it is necessary to completely hermetically seal a space between the nozzle member 911 and the case body 904 in order to prevent the coolant from leaking therefrom. Accordingly, in a case of setting a height of the nozzle member 911, for example, in consideration of the tolerances in order to give priority to the sealing between the nozzle member 911 and the case body 904, then a gap 930 could occur between tip ends of the nozzles and end portions of the fins as shown in FIG. 10A.
When the coolant is flown in this state, then as shown in FIG. 10B, the coolant leaks through the gap 930 as shown by arrows 931 even if the coolant in the inflow passage 913 is ejected from each of the coolant supply holes 912 toward the fins 902. Therefore, in the cooler according to the related art, the coolant, which should reach roots of the fins, leaks from the gap 930, and a velocity of jets ejected as shown by arrows 932 is lowered. Accordingly, the cooler according to the related art has a problem that cooling performance thereof is lowered.